(a) Field of the Invention
The invention relates to a color filter substrate, and more particularly to a color filter substrate using interference filters.
(b) Description of the Related Art
The color filter is a critical component for a color liquid crystal display (color LCD) since the former certainly determines the color performance of the latter. Further, the color filter often takes up a high percentage of the overall fabrication cost of a color LCD. FIG. 1 shows a schematic diagram illustrating a conventional color filter substrate 100. Referring to FIG. 1, a black matrix 110 is spread on a glass substrate 102 and defines a plurality of opening regions in which red, green and blue color filters 104, 106 and 108 are formed. The black matrix 110 is used to improve the display quality by blocking the stray light passing through the gap between the pixel electrodes (not shown) that correspond to different color filters. Also, a transparent electrode 112 is formed on the top of the black matrix 110 and the color filters 104, 106 and 108.
FIG. 2 shows a flow chart illustrating the steps of a pigment-dispersed method that is most widely used in the fabrication of a color filter substrate. The steps of the pigment-dispersed method are similar to typical semiconductor photolithography processes. First, a dyeing photosensitive material is applied to the surface of a glass substrate having black matrix through a spin coating process. Next, the dyeing photosensitive material such as a red photosensitive material is exposed through a mask and then developed on selected areas to form red pixel portions on the glass substrate. This procedure is repeated for green and blue dyeing photosensitive materials to form green and blue pixel portions. Finally, a passivation layer and a transparent electrode are sequentially formed on the colored coatings to complete the fabrication of the color filter substrate.
However, such fabrication method obviously has the following disadvantages. First, with regard to the fabrication process, its spin coating process through which the dyeing photosensitive material is coated on the glass substrate results in low utilization efficiency of raw materials and thus increases the fabrication cost. Further, as to the color performance, the red, green or blue light filtered out by the color filter substrate fabricated by the pigment-dispersed method has low spectrum resolution to result in an unsatisfactory color saturation of a color LCD.